#include <iostream>
#include <vector>
using namespace std;
class Solution {
public:
    int uniquePaths(int m, int n) {
        vector<vector<int>>dp(m, vector<int>(n, 1));
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m-1][n-1];
    }
};
class Solution {
public:
    int uniquePaths(int m, int n) {
        vector<int> dp(n, 1);

        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                dp[j] += dp[j - 1];
            }
        }

        return dp[n - 1];
    }
};